She doesn't have to. Your AST is due to expire on 25th July, she is stating that when it does, you need to be leaving.
I don't like the you leave on 25/7 and we will carry out an inspection the following week. Not one bit.
Who will be conducting the check out when you actually go then? You need someone on 25/7 at 12.00 to check you out properly.
You may need to instruct an inventory clerk yourself this company does them for tenants for a start No experience of them, but it's worth you considering, cos you KNOW this landlady will be unreasonable.
Should you not wish for further disturbance at the hands of this creature, you can refuse all visits including prospective tenants if you so wish. Doesn't matter what your agreement says, if your privacy and right to quiet enjoyment is being compromised, there is nothing she or any one else can do - bar a court order which takes MONTHS - to force you.
You have to face facts, she is going to be trouble. Be prepared. Do the maximum you can do to erode her reasons for taking your deposit. If you are unhappy, do not hesitate to go to the TDS Dispute service, they ROCK and they won't stand for any of her unreasonable nonsense. 90% of the time they rule in favour of the tenant!
I'd recommend insisting on an independent inventory clerk to check you out. If you don't get on, HIRE one yourself!
Was the house/carpets/oven cleaned professionally when you moved in? If so, you have to have them cleaned professionally with receipts to prove it.
Move out a week before the 25th and spend the remainder of the tenancy making sure that place sparkles. This is not about her, it is about her trying to claim YOUR MONEY!
Photograph it to bits, remember the washing machine powder compartment, the extractor fan, all switches and power points, light fittings, skirting, everything.