After quite a lot of research I decided to get a Btwin Hoptown 300 which is
Decathlon's most basic at £130. Main differences from the 320 are that it is £50 cheaper, single speed and doesn't have mudguards or folding pedals. Everything else is the same and overall the 300 is a bit lighter thanks to having fewer bits.
Ideally I would have got a Brompton but cannot justify the cost. Wanted a simple bike to store in my car boot and use for mixed mode commuting and getting into town centres, hospitals etc without paying for car parks. Also thought it might be useful to explore places on, particularly where it is OTT to take a proper bike and activities may require it to be locked outdoors.
Have used 4 times now. Everything works as it should and it seems a fine ride. Comments about poor ride and Flexy hinges not borne out by evidence of use, including up and down short steep climbs and sections of the transpennine trail. The fold isn't the neatest as there is nothing to stop the bars swinging about. Not a great problem and I will devise something soon using bungy, Velcro or a toe clip strap. I am loading it into the car leaving the seat post raised. It is quick to fold and unfold and locks together firmly with no play in the joints. It wheels along fine when folded with the seat post still up. May be useful when changing trains? It comes with basic front and rear lights and a bell. I am using the seat post a couple of cm beyond the limit markings. Plenty of tube remains in the frame but ideally the post needs to be 10cm longer. may replace at some point but happy with the setup for now.
Due to its non flashy appearance and low cost I will have little hesitation in locking it up outside when in town rather than having to take indoors. Happy to use a wire lock than heave around a U lock.
The 300 has all the frame bosses and hanger for gears. The hub is the same as the 6 speed but has a single cog freewheel. I may convert to six speed at some point as I have all the bits spare from converting an old road bike to single speed a while back.
For its intended purpose I am really pleased with it.
Thought I would post this as other threads by people seeking advice about cheaper folders often diverge from the original questions.