Check with the hospital as when I had chemo they arranged for me to see a wig specialist at the hospital. Also the NHS pay some of the cost of a wig so it's worth making enquiries.
Like Welshwife I didn't wear my wig very much as it felt like wearing a dead rat on my head. All I would say is, if and when you start losing your hair, have it all cut off and just wear scarves/turbans. Perhaps I was lucky as my hair started growing again very quickly and I really liked it when it got to about an inch or just a bit longer.
Also check to see if your hospital uses the Look Better Feel Good charity which gives great advice on coping with skin problems, make up, etc. during treatment.
Wishing you well for your treatment.
I hope your treatment goes well