Are you referring to Deers leap park in East Grinstead? If so, for the time being at least, i’d give it a miss. I took one of my daughters there in the driest part of what we called summer last year and it was utterly water logged, it has not exactly been dry since either.
If your looking for trails in that area though i’d steer you towards Tilgate forest, which is only down the road and is better drained and has more interesting trails.
I’d happily show you around there if your not familiar with it, although i work shifts and do most of my rides mid-week. My e mail is in my profile if you want to get in touch or you could try the forum over at sussex-muddy@rse, theres a group that ride most wednesday evenings and weekends.
All that said if DLP does dry out properly then i’ll be back this summer as it is a good place to take the kids.