I have only ever sailed in the Swan river in Perth and want to a have go at sailing in the sea (probably Leighton). I happly sail around on an old 115 litres F2 ride but I am not sure if would need to get something more ocean/ wave orientated.
I am about 99 kg's
I can waterstart and gybe (60% of the time)
Do I need to get a new board for the ocean. And if so what sort of thing? size?
As long as you mean gybe 60% of the time but waterstart every time 
The board will be fine, you will notice that your gybes may improve as you can gybe on the face of a bit of swell and it will help carry u through a bit more without dropping off the plane
If you can handle the slop in the river on a real windy day then you will be fine in the ocean when it is not blowing too hard. I'm a simialr size and use 111L starboard carve near home off south beach on a regular basis and it is great. If it is windier that 5.8 weather i use a smaller board but that is only because I can.
Sail from Cottesloe as Leighton is full of kites and you get to rig on grass as well. Just ask for a bit of local knowledge from someone else on where to launch or follow someone out. There are some rocks on the waters edge. South Beach is good to but you might be out on your own.
Try before you buy. Give it a go on the board you have and then if you want to upgrade borrow a couple of demo boards from the local shops.
I've also found a 111L Carve is fine in the ocean/surf. Was using up to about 4ft waves with no problem, 5.7 and 6.4 conditions.
Set your straps inboard, mastfoot all way forward.
Actually it is often easier (see less joltingly rough) in the surf than mega choppy flatwater/bay conditions, more fun too 
... now you're going to want a wave board. Personally I've picked up a cheap FreestyleWave that may eventually replace the carve.
I can handle the slop/chop in the river.
More worried about when there is a lack of wind.
I find the board very tippy when the wind drops and the dark imaginary shadows in the ocean are more worrying than the ones in the river.
Was wondering if a newer shorter/ wider style board of similar/smaller volume might give me more confidence.
Or am i being a wuss
Na not a wuss, it's just the unknown, you're lucky you had a river to learn on.
Leave your gear as is, that's what you're used to, pick your day and make sure there are others out. After doing that a few times you'll work out what you want and how you want to do it, have fun 
I attempted that for the first time yesterday evening at Brighton Beach, after spending many happy sessions at Pelican Point and the (protected) beach area at Lancelin. I just wish the wind had been a bit stronger yesterday, so I didn't keep falling off :(
I was out on my 127L f2 Stoke with a 6.0 sail and it was handling the waves rather well, given the relative lack of rocker on it, popping over and through the break just fine.
First few times out, go on a board that you are comfortable on.
Leighton and Brighton tend to have water that surges a lot in the 20m between the beach and the back of the break, which pulls the board around a lot. Make sure you can do standing starts real quick and keep an eye on the wave cycle, so you can pick a flat section of water to take off on and get through the break.
I wouldn't recommend starting out at Brighton beach unless there's practically 0 swell or you've already got well honed wave-reading skills.
Strong downwind current that kills your apparent wind, dumpy waves, kiters, windsurfers, kayaks, swimmers everywhere and the odd buoy makes a recipe for disaster (read as kit destruction) for newbies.
There are plenty of good places to cut your teeth in the sea around Perth metro:
[url="www.google.com:443/maps?f=q&hl=en&geocode&q=john+wilkie+wa&sll=-31.805664,115.726976&sspn=0.0186,0.038624&ie=UTF8&ll=-31.805993,115.733242&spn=0.0186,0.038624&z=15"]
Pinnaroo Point - Lacks a shore break and is great for getting used to sailing in "3D" especially when there's a decent swell. Good initiation but don't spend too much time here if your goal is wave sailing.
Dutchies
maps.google.com/maps?f=q&hl=en&geocode=&q=cottesloe&sll=-31.805993,115.733242&sspn=0.0186,0.038624&ie=UTF8&ll=-32.007057,115.751621&spn=0.00464,0.009656&z=17 - Rarely picks up a decent swell in summer so is a top spot for bump n jump or small wave sailing. There are a few rocks so ask the locals to point them out before you set out.
Leighton beach
maps.google.com/maps?f=q&hl=en&q=Leighton+Beach,+6159,+Australia&sll=-32.007057,115.751621&sspn=0.00464,0.009656&ie=UTF8&cd=3&geocode=FRFKF_4dkS3mBg&ll=-32.027179,115.748241&spn=0.009278,0.019312&z=16&g=Leighton+Beach,+6159,+Australia&iwloc=addr - Has already been discussed but this is a good summer location when the number of kiters is low.
Mullaloo Beach
maps.google.com/maps?f=q&hl=en&geocode=&q=mullaloo+beach&sll=-31.775607,115.743456&sspn=0.035462,0.077248&g=mullaloo+beach&ie=UTF8&ll=-31.784874,115.732706&spn=0.009302,0.019312&z=16&iwloc=addr - Further north, Mullas is a good beach break training ground. Look for a small swell or a high tide for minimal white water. However newbies should be fine in anything up to 2.0m swell (Rotto reading).
