I would also advise you to seriously look at BK subs. they are excellent. They are in Southend-On-Sea. For US readers that is on the North side of the mouth of the Thames estuary. So it faces south to Sheerness on the Isle of Sheppey at the mouth of the River Medway.
BK are in the huge industrial estate that has grown up at the back of Southend.
I visited Southend on my last visit a year ago. It was a lovely evening and I had fish and chips on the sea front. The pier at Southend is two miles long with a train service on it!
I used to love to visit Southend travelling from Strood pier on the old Medway Queen.
This is all topical now with the movies Dunkirk and Darkest Hour.
The Medway Queen is a veteran of Operation Dynamo and made multiple trips to the beeches rescuing 7000 soldiers. She is the only surviving veteran Dunkirk paddler. Restoration not yet complete, but I hope she is put back to steam in my lifetime.
This is an account of her exploits to the beeches of Dunkirk.
May be this will be a good excuse to visit Southend-On-Sea, a place of which I have fond memories.
Medway Queen as she is today at her berth at Gillingham Pier on the River Medway.