if you want to cash in your chips 2 ways you can do it. (dependant on the amount your anticipating of getting).
have the whois changed to a company, (you would have to have owned for 2+ years,) then instead of selling the domain, or portfolio, sell your shares of the company. end results 10% income tax on it. can stay in the uk and do this one. always leave a few semi dormant or late return companies around for this very reason

then just file the accounts including the domain. - if you have only sold 1 name before, and dont do it regularly, if you have held it for 2 years - can get the taper relief anyway, no need for company.
otherwise, make a few dummy trades for a few thousand, (buy xzxcz.com for £500, sell it for £1k, etc - to friends if necessary) - to remove the capital gains element of your sales status, and make it certain your trading. can also pay vat etc on these sales et (assuming over the 60k or whatever turnover). Before april 5th 2008 leave the country for one year - to either a non tax haven (dubai,most carribean,andorra etc,) or to a country where they don't tax your foreign earnings, i.e. thailand, malta etc. Then make the sale in may 2008 just to make it clear cut, (1 month after non resident) . In this case, you dont need to pay anything at all to inland revenue for that big sale. (definitely worth doing if its over 250k, as 100k+ tax savings).
to be even safer, dont sell to a uk based entity. as they might argue the funds originated from the uk even though your non resident. (can also be a very very small risk if you get it paid into your uk bank account as thats a uk trade).
in terms of getting paid in $ into the cayman islands, that is not necessary, any non uk bank will do. (personally dont trust many offshore banks, so choose a reputable one in isle of man, jersey, or luxemborg,swiss)
Both methods above are perfectly legit. wherever you choose (thailand is a good choice, live comfortably for 12k over the year,+ if your single i dont need to say anymore). i find most accountants, are not creative at all. so you usually need to come up with the idea, and then pay them to sign it off.