Would sealing a bricks/block paving drive with polyurethane sealant be a good idea if the drive is sloped towards the house?

if your drive has just been layed [ within 8 months] sealing it will keep in the white effloresence that comes out of all concrete products. let all that come out then do it. i would recommend using marshalls keybond on fresh kiln dried sand it seals the sand and stops growth. you still have to brush your drive as seeds will always take hold. after sealing you can hose drive down and sand wont move. as for water i would definatly put aco channel drain to front of house and tap into nearest gulley/manhole [on your property] as water will do untold damage to building.

You would be wasting your time sealing block paviors, to try to stop rain water going down a slope, theres to much movement in paviors to seal the gaps. The proper way is, mark 150mm line from your building, string a line and cut through the blocks, dig down and fit proper drainage chanels with removable grids, bed these in concrete and surround, make good. Ensure you fall your chanels to a rain water drain or good soakaway. In response to your edited question, the only way you will stop the weeds is regular use of weed killer, this normally happens when the preparation of sub base is not done right, ie plenty of hardcore. Also noticed advice about sealer, you will be wasting your time and money, thats my opinion, you can pressure wash your drive to clean it up then spread some more kiln dry sand over, I cant imagine how sealer is going to fill the spaces between the paviors, but if thats the way you want to go then try it. We have done loads of drives with no problem, and I dont know any one who has used a sealer.

The reason most people seal drives is to stop the weeds growing in the joints, it also brings out the colour in the blocks and slows down the fading due to the ageing effect of the sun. When it is raining very heavily the joints between the blocks will absorb very little water, so the water will end up against your house. You need to install proper drainage to remove the flash flooding risk which you currently have.

you can buy all the weed killer from uk and next year the weeds will be the same,do not seal the driveway if the level is towards the house and should have a drainage Chanel fitted with the driveway idiots and cowboys on the job thats for sure have a proper drainage fitted by the house regards peter

you do need to seal the blocks if you are concerned about the water you need acho drains fitting between the house wall and the drive to take the water away