The first thing you're going to need before you start taking payment for your services is insurance. There are several companies available to you: The Guild, Babtac etc. Once you've got that sorted, the best thing to do is to google mobile therapists in your area and check out their prices.
As for advertising your services take a look at my more ways to promote your business thread for some ideas.

I have insurance ( i took this out after i passed 1st formative) And i did actually donate a free facial to the local schools Christmas Fayre. I have a client base, however they were my guinea pigs, and it seems unfair to charge them now lol. Have googled local travelling therapists, and found none locally --- maybe thats a GOOD sign very confused x

Google "mobile therapists essex" mobile therapists essex - Google Search

There are two companys at the top of the listings and numerous independents I'm afraid. This doesn't mean there is no space for you but don't be fooled into thinking there is no competition. There is no reason a mobile therapist cannot offer all treatments in a salon. I would start charging my "guinea pigs" from now on as you can't give away treatments forever if you want to become a professional business. I kept my prices similar to salon prices but had 3 years salon experience under my belt, but do some searches on the geek site for more info on starting up and good luck.