Gerald, welcome to the nuthouse.
As you will have read this game means different things to different people, therefore you can either build a lucrative business, or make a wage to meet your needs. The choice is yours and it doesn't matter if your views differ from others.
If you wish to make £7.50 an hour and it meets your needs, then no one should criticize you for this. However, as has been said, there are overheads to meet which will need to be taken into account. Most guys on here are WFP, for which the overheads are higher, or you could start by going trad (far cheaper and will get you started).
If you haven't done window cleaning before, it may be an idea to gain some experience by helping a windy with his own work, or you could practise on your own windows and build up some confidence. It will also give you an idea how long it takes to do a house like yours and gauge how much you could charge/earn from similar houses.
Best wishes,
John
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