Dont give up on it Roobarb, the £30 is well worth the info it provides. Getting my Uncles RAF service records opened so many doors for me and rest assured that there are many folk on here who will help you with any codes or other info you may not understand.
I sent the kinship form, the fee and a letter of authority signed by my Dad who is the next of kin. In your instance, l am sure you will be successful if you explain the circumstances. Go for it!!
One thing to remember also, ask for photocopies of the actual records or you just get a printed summary. Sometimes they include a glossary of terms for your assistance.
Good luck, let us know how you get on.