If you have an established site it would be worth retaining this as opposed to a domain switch.
Mack.
Do you think that if I change change domains this will have an impact on SEO/loss of aged domain? What do you suggest I should do? What considerations should I take?
It can have serious implications if not handled correctly and can lose you all your hard work. Have a read of this post about a 301:
[webmasterworld.com...]
If you are getting to take your entire site as it is now, URL structure, the whole lot, and move it to the new domain, upload the site and then from your registrars control panel point the .co.uk to the new domain and DELETE completely the original site, then it should go relatively smoothly but expect a 3 month delay in regaining rankings.
Do not under any circumstances release the .co.uk if you have a lot of backlinks pointing at it. If you only have a few non-essential ones then it's ok to re-use once the SEs caches are showing clear after about 3 months.
Whatever you do duplication is a big issue, ensure everything is all done at the same time and the transition will be pretty smooth and painless apart from the waiting process whilst the SEs re-cache etc.
Well, that's been my experience and it's always worked pretty well:-)