New lawn

Ive filled in a large pond which covers about half the garden,im preparing this area for seeding -if i reseed and grow new grass here will it look a lot different from the rest of the garden were the grass is quite old?also is it to late in the year to seed?thanks...

 

some people say that we are now too late in the year to sow lawn .... however, B&Q sells lawn seed that is labeled as fast germinating

if you sow seed now, and we get a few more days of warm weather, it could/should germinate in approx 2 weeks, provided that you keep the soil moist

from what I have learned, autumn is the best time to turf

the new grass will look different from the old for a while, but in spring, add a high nitrogen fertilizer over the whole area and it will look good (assuming that the seed you sow is the same type of grass (or similar) to what you have already have

if not, in spring, add some lawn dressing on the old lawn, and overseed with the same type seed that you have used on the new patch

 

Depends on several factors.

What sort of condition is the existing lawn in?
What type of grass is in there? No need to be too specific, but generally you get what the garden centres call ornamental or hard wearing lawns. Ornamental ones have really fine grass in, whereas the hard wearing ones tend to be a bit coarse. If you want it all to look the same, you'll need to choose your grass seed wisely.

Is the soil that you filled the pond with the same as the soil under the existing lawn?

Apart from all that, I'd still sow seed now if the ground is ready, but wouldn't leave it too much longer. Don't know what its like in your area but up my way winter tends to just turn up one morning. It can be unusually mild for ages, and then we come out one morning to find our house has been transported to Antarctica in the middle of the night. Ok, I exaggerate, but not by much.