There's too much fear about TM's on this forum. Owning a TM is far more complex than simply registering a word or words, they're only granted for tightly defined categories, often only granted on a graphical rather than text mark, sometimes granted with strict restrictions on what is covered and importantly, you can't register a domain name as a TM.
As a domainer the critical thing is not to be seen to be taking advantage of the goodwill built up by a TM owner, so there's no issue registering mcdonalds.co.uk and selling nuts and bolts but there is if you start selling prime hamburgers.
We bought the domain frontrow .co.uk recently with plans to build a ticketing site. It wasn't a cheap domain and knowing how big business works I decided it might be an idea to apply for a TM to cover us against anyone else coming after us down the line. The application was rejected with no right of appeal on the grounds that it is too generic of a term, the only thing that we were advised to do was to register something graphical, a logo etc..
Like I say, don't be paranoid about TM's and if it's really important, take advice from a professional, it's often not cheap but it could save you a lot of hassle and cost down the line.
A small tip, the basic fee for a TM is £170 but something that isn't very clear on the IPO website is that you can pay half of that and have your application examined and a decision in principle. If you get the green light, you pay the other half, if your application is rejected it's only cost £85 rather than the full £170.
