Hosting has got nothing to do with owning domains. I put a bit about buying domains on my site
http://www.domainpairs.com and this may help you. I wrote it about a year ago, so maybe I should update it soon.
You need to separate .co.uk domains from international domains (.com etc). For international domains, I think you should use registrars like On Line NIC - cost should be around $7-$8 per domain per year and no transfer charges.
Some hosting companies link domains to other services and charge a transfer fee if they lose the income from these services.
For example I have a "free" domain with freenetnames, but if I want to move it from them, I need to pay ã95. To use the domain. I need to use a dial up service via their ISP subsidiary.
ã500 a year sounds a lot for hosting. You can get virtual hosting for around ã10 per year. You can also alias multiple domains to this one site. It depends on your bandwidth/storage requirements. I also have a muti- site hosting account where I pay $26 per month for 50 GB of bandwidth.