Suggest an AST Contract with Break Clause

Can anyone suggest an AST Contract with Break Clause please.

I know OR do one, so do LandlordVision but I wanted to compare a few before deciding what fits our situation best (and even what actually looks the best to the eye).

The Break Clause with OR states that notice can be given in month 4 and 2 months notice is required - so effectively a 6 month term.

Is it legally permitted to enter into the Contract “This Contract can be mutually ended by the Tenant and Landlord at any time during the Term if the Tenant so requests in writing and the Landlord so agrees in writing. A £50 charge may be payable by the Tenant to the Landlord to cover the cost of re-advertising the property.”

The thinking behind it is not to have tenants in the property who dont want to be there, whilst also covering the cost to re-advertise (such as the OR fee).