[rl]

Hi, Unless he (or someone else) is

a) trading under that name (or something very very similar) or
b) he has registered the company under that name with companies house (which he hasn't, just searched and there is only WETHERBY WINDOWS LIMITED) see http://wck2.companieshouse.gov.uk/8aed40dda4c55067a0e7e1bc41a01433/companysearch?disp=1&frfsh=1254389724#result
c) has a registered trademark for the name or a very similar name (which he hasn't) see http://www.ipo.gov.uk/tm/t-find/t-find-text/tmtsearch-default.aspx

then you are free to trade under that name. He could only sue you if he was activley trading using that as his business name or had b) or c) above.
There is no need to register your name with anyone as once your trading using that name no one else can trade using it in your area or you could sue them.

I can't see that Wetherby windows ltd can cover wetherby windowcare.

See http://www.businesslink.gov.uk/bdotg/action/layer?r.s=tl&r.l1=1073858805&r.lc=en&topicId=1073859131 for official advice from government department and maybe give them a call to seek their advice.

[rl]

also a good site for business advice is UK business forums, just type that into google. They have a legal section where you can ask questions and i'm sure someone will help you there.