Window cleaning - how often and how much?

[IToldYouIWasFreaky]

I am trying to find a window cleaner as I have left it far too long and the sun shining through my windows is showing up what a total state they are!

So, trying to get quotes and get someone booked on a regular basis. How often would I need them done? And what's a reasonable amount to pay? It's a standard 3 bed semi with a conservatory in the SE.

I pay £14 for our house, it was a 3 bed semi - now a 4 bed as an extension was done over the garage (so it is a top heavy house).
No conservatory though.

Ours comes every other month roughly - I'd prefer monthly but we live rurally and he won't come out more often than that.

Someone else in the village has a guy that charges £25 for a smaller house than mine - he comes more often but I think that is too expensive, so prefer my £14 version even if it does go a bit too long in between! He also takes bank transfer, so just puts a note through the door when he has been and I pay him. I don't know in advance when he is coming unfortunately though!

Thanks! I have just been quoted £17 which sounds pretty reasonable