Visa from Hull question.

Fred the cost for a multiple entry non Imm O visa - reason, visiting family & friends is either 100GBP or 110GBP.
That will give you multiple entries (no limit) into Thailand for a year from the date it is issued to you. Each time you enter Thailand you will be allowed to stay for 90 days, but then must physically leave Thailand to get another 90 days. In this way if you make your last entrance into Thailand just before the visa expires you can stay here for 15 months on it.
Multiple entry tourist visas are also available, but I do not believe these would/could benefit you more, as you have to exit Thailand every 60 days (or pay 1,900 baht for an additional 30 days).
Everything you need to know about visas is here - including fees & the forms to fill in.
http://www.thaiconsul-uk.com/downloads-and-visas.aspx
Personally I cannot recommend the Hull Consulate highly enough. Their postal service is excellent - send 1 day, get back 2 working days later is the WORST they do.
If you have a specific question (even after reading all the information) then an e-mail to them will get a quick response & advice if you have asked for it.