Hi Jo- Anne,
Longleat is a great site and maintained to the usual CC high standards. We've been there twice, for long weekends during the past 18 months and thoroughly enjoyed it.
The first time we went there (which I think was towards the end of May) the male California Sea Lions (residents of the Lord Bath's Half Mile Lake) barked continuously day and night. This is what the males apparently do during the mating season to impress the females. As the lake is behind the site, depending on the wind direction, it was at times a little loud but you got used to it.
As Claire and Rob mentioned the Tesco Clubcard vouchers can save you a small fortune. The first time we went we did all the Longleat House / Safari Park attractions during the course of the weekend. The second time we went (last Summer) we only went to 'Adventure Castle' playground as our children absolutely adored the place. It's about 3 mins walk from the site and has climbing frames, rope bridges, tree houses, giant slides, trampolines and best of all a 'Splash Zone' where the children can get soaked by jets of water that dance out of the ground.
The bus stop for the Safari Tour Bus is also just outside the site.
A tour of Lord Bath's House is worthwhile as is the walk through the gardens. In the Great Hall within the house there are a couple sets of prehistoric Deer antlers which are absolutely huge! I can't imagine how big the owners of the antlers most have been!
If you decide to take the Safari tour, by car, then think twice about driving through the monkey enclosure. They are little gits! You drive around laughing at others whose cars are being surfed by the monkeys whilst they strip rubber bits from the cars. I thought that I had got away without being vandalised until when I came to use my back windscreen washers two weeks later! They had pulled out the nozzle chewed through the pipe but expertly replaced the nozzle so that their handy work went unnoticed. The subsequent leak through the roof lining was a royal pain in the posterior!
The site is a great venue and well worth a visit.
Cheers.