Paul, before you go let me tell you what I know about the R. Crouch.
I've fished the hole in the wall lots, why I kept at it I shall never know, it's crap. A long walk for nothing. Why not set up on the jetty to the left as you face the customs office on the wall,the boat jetty that is next to the timber yard, not the new one. The security guy can be a bit funny, it is private, but I normally get away with it, be nice to him and don't turn the light on. There is often a boat moored which makes life a bit difficult but if its empty chuck one straight out and you might get the odd whiting or dab. I use mackeral for whiting and lug for dabs, frozen blacks if you can get them. This time of year you can feather for herrings down the piles of the jetty. The tide runs at about 20 knots under the platform and there is no barrier, be v v careful, out in the main channel it will rip a 6 oz grip lead straight out when it's running hard. I'd advise you to do what I did, find somewhere else to fish, Kent coast is 2 hours drive from me but I can catch fish there.