I agree.
.org.uk domains are not that great unless you are a charity or already have the .co.uk version and are preventing people like yourself getting hold of them.
As a trade mark you need to be careful or you may find yourself in court! It has happened before with domains like the famous 'phone4u.co.uk' case. As a domain, I can't see too many people going on your site, especially as the company advertises so heavily for their official version.
I wouldn't risk trying to sell it to lombarddirect in case you spark a dispute, and I can't see anyone wanting to buy it from you. I really can't see a price on this domian and as grantw said it may cost you more to keep it.
alex