Google have sent me a voucher for £50 to spend on adwords. Trouble is, I've no idea what the hell to do with it
£50 will not go very far unless you are very specific. Some starting points:
Think about your brand name & misspellings (for example I couldn't find you on "Brian MacIntosh"). Check variations of as well e.g. brian mcintosh photographers, brian mcintosh photography. Bryan mcintosh photographers (and variations) also worth including.
Then combine specific types of photography with specific locations e.g. commercial photographer north east scotland, commercial photographer aberdeen.
For small towns very near you you could try "photographer laurencekirk"
Until your confidence increases, you also want to make sure that you either put all phrases in as exact match (put keywords in square brackets e.g.[photography laurencekirk]) or learn about negative keywords (a big one for you is probably "wedding".
(Tip for website: add your address - it provides credibility - do you really want to risk losing out on that ad agency deal to photograph your local area just because you didn't put an address on the site?)