I started caching a few years ago and there used to be a cache within the church grounds here (A Grave-end-ever. It was approved with the Church at the time but things change and the cache was archived. I had a break from caching (having twins slows you down!) and when I restarted, I noticed that it had been archived. It's a cracking spot with the impressive and imposing Tattershall Castle standing tall in the Lincolnshire countryside and Holy Trinity Church Tattershall, part of the Bain Valley Group of Churches on the same monument site. It's really deserving of a cache as you get two beautiful buildings dating from the mid 1400's for 1 cache stop. As you wander around the site, you can sometimes observe the local bowls team playing, look around Holy Trinity church during opening hours, wander around the cemetery and Castle's Tiltyard (where the jousting tournaments were held) and maybe even visit the castle itself.
If you're caching during normal opening hours I recommend the nominated car park just down a short driveway. It's not too far from GZ and if you have cachehounds with you then its a good spot to give them a leg stretch along the River Bain. Caching outside of normal hours there is off road parking very close, in front of the Castle entrance (be aware its the access point for the disabled drop off point - but you should be fine when it's closed).
There's a few other caches in proximity, Tom Thumb (virtual) and the nominated car park is also one of the car parks identified in the description for Timothy Potter (part of a local multi - well worth doing!), so if your not just passing through there's a few other caches to make it a worthwhile stop.
The cache - is a magnetic nano 15mm x 10mm, so you'll need a pen. Happy hunting!