Hi Ronnie
The insides take longer but are usually charged at a lower rate. This is because there are no special equipment requirements. Hence, you are quoting against the office cleaners who tend to be cheap (£10/hr or less). You will be quicker than them (twice as fast) This means that the most you could charge would be £20/Hr. The exteriors however may be £30/Hr (£10/Hr for your equipment and £20/Hr for labour).
Then you have to decide how much travelling time , paperwork and hassle ("Admin costs" as I like to call them) is involved and add that to your total.
Finally, decide how much you want the work and adjust your prices up or down accordingly.
PS. I think you are a bit cheap at £30 for the 45ft stuff. Your staff will need extra time for breaks at that height. I would recommend charging an extra 25% for the stuff at that height.
Regards
Steve