Welcome to the forum. I agree with Richard B that it would be worth taking your level 2 RYA course prior to buying your RIB, test as many RIBs as you can before buying and don't just go out on fine days, you need to see how they handle when it turns nasty. I have had several RIBs but now have an Avon 620 with a Yamaha 115 4 stroke, bought it at the Southampton boat show in 2000 from BHG Marine, they now have a new showroom in Lymington.
I had the opportunity to test a number of RIBs at the Southampton boat show but when the conditions got rough only Avon kept going. The only boat that I would consider other than Avon is Scorpion, would love one but it means changing the car to tow it and would cost considerably more than an Avon. I tow mune with a Nissan X Trail 2.2 Diesel.
Good luck with looking, have a look at mine on my website:
It has the sort of layout that you are looking for.