Buying my first property

[Allbymyselfagain]

Ok so finally nearly got my 10% deposit. Have definitely got my 5% and fees and should be sorted in next few months. Got an appointment with a mortgage advisor in next few weeks to get my mortgage in principle (I think it is) so that I can start looking for a home. I'm going to get quotes for both 5% and 10% so I can see difference in monthly costs etc. I hope by time I find somewhere I will have the 10%.

I'm wondering if I only have enough for the 5% now would they give me a 10% mortgage in principle and whilst my credit report is excellent I do occasionally go over drawn and I do use a credit card for work that doesn't always get fully paid off each month. Is it likely that the mortgage in principle will be approved but then the final decision rejected? I'm a first time buyer and worries like these are making me want to cancel the appointment! Any advice?