Moving house, giving notice etc

[Gorja]

So the master plan of moving 2+ hours away is coming together.
I have a new job starting on 15th August. We have found and had offer accepted on a house to buy. We are currently you aiming for surveys and searches to come back. No chain which is good.

So we currently rent. Six months lease agreement comes up on 28th June. No contact form landlord or estate agents so it will turn into a rolling monthly contract.
I don't want to be in the position of paying rent and mortgage for a month. So when do I tell the landlord we are moving when we don't actually have a date yet? Do I risk giving him notice now that we are moving on the 3rd August which is the date I asked the solicitors to work too or do I wait till I actually have a date? Can I give six weeks notice instead of four or will we be expected to be out within four?
As I said I don't want to pay twice but I also don't want to be homeless with four kids!
Can somebody talk me through it as the more I think about it the more confused I get!!

Not advisable to give notice until you've exchanged - it doesn't always follow that a short chain means a quicker transaction because there could be legal matters which have to be dealt with before exchange can take place. Perhaps save some funds just in case you have an overlap with rent/mortgage, not ideal but you would potentially risk being homeless otherwise.

I agree with Spickle. You normally have to give notice in line with rent day. If rent day is 28th then your tenancy would end on 27th of any given month (provided you gave notice by 28th of the previous month). Staying for a part-month is entirely at the landlord's discretion.

Not until exchange. Way too risky.

Exchange date. That's what our solicitor advised us and it makes sense. An extra months rent us annoying but actually gives you time to move out and get the place cleaned for your deposit return...