Thanks for replying guys, when I first started out I hadn't a clue how much to charge and so I based my hourly rate on what people were charging on freelance websites but I see now that those rates are much different to the ones you guys are charging. Honestly I think, here in Spain at least, if I put up my price I just wouldn't get any work. If I had steady work at the price I'm charging I'd live quite comfortably. With regards to the London work.....I'll have to have a serious think about it....it's not so much the price that bothers me....I just don't want to be taken advantage of. Plus I don't want to be accused of undervaluing the work we do. I've attached a link below to the image I was talking about...hopefully it works.
I think, with regards to London anyway, like Philippe says, I'll have to up my game and then charge more.
By the way, websites like this one have helped me to improve my work a lot....so thanks a million!!
http://niamhl.wix.com/interiorarchitect3dvisualiser#!portfolio/vstc1=commercial