We've got a BCT 4m bell tent as well. Had it about 3 years. It's a pretty much standard bell tent shape, well made and solid. Ours has a zip in groundsheet, which is attached with 2 very substantial YKK zips. The standard centre pole is a big steel thing, which we replaced with a wooden pole this year.
The service from BCT is extremely good. The only problem we've had is, due to some mix up at time of manufacture, we've had trouble getting the door frame to fit just right. BCT have supplied us with a range of different poles to try and get things bang on. That's not actually much of a problem though - bell tents are designed such that you can just stick a single upright pole in the middle of the door and it works fine.
The vents around the outside have a drop down flap that buttons with a toggle and some elastic. Venting is good, waterproofing is superb. We were on the headland at St Davids in the 2012 summer storms. We stayed dry as a bone and stable all night. The tent flapped a fair bit but never felt the least bit unstable, unlike all the modern tents we found stuffed in the bin the following morning.
We have a smallish awning on the front of it, which was from BCT as well. It takes some tinkering to get it to look just right, and there isn't shedloads of space under it, but it works well as a porch. We sometimes lift one side of it to keep the rain off while we eat. You do have to watch your feet though, as there's plenty of opportunity to stub your toes on wooden tent pegs