Daniel, if you're starting to get some lucrative contracts which seem to be possibles for ongoing work (lucky sod), why not invest some of that money into ensuring that you correctly tie them to long term deals. I assume you're talking about maintenance programmes?
These contracts may turn out to be big bucks, so would you not be prepared to pay the equivalent of, say, one of those commercial jobs to ensure you have a solid set of T&Cs? I know I would.
£140 p/h sounds a lot, but if your solicitor's worth his salt, he'll already have a standard set of service industry T&Cs and will just need to tweak them a bit for your own business. I'd be surprised if he needed to work more than a couple of hours on them.