Update:
Hot brake 1:handbrake adjustment nil.
So I've done around 350miles and it was alright for the first 200 also and then I stArted to feel heat and once again my mpg started to drop. I've got a feeling it's a sticky caliper but I will put it apart.... do the slide bolts as doing this I won't disturb the brake fluid and have to do a bleed. And if this doesn't work then ilk replace the caliper
Bear in mind when slackening the slide pin bolts that the bolt screws into the end of the slide pin that while turning the bolt the slide pin can also turn, there are some flats or a hexagon on the slide pin (around 17mm), just where the rubber concertina gaiter ends, the area for a spanner is not very wide and I used a bicycle spanner (only about 4 mm thick) to hold the pin - also make sure when re-tightening the bolt that you hold the pin as otherwise the gaiter can get twisted - you can get a normal width spanner in if you can push the gaiter out of the way, but it can be tight and I never wanted to risk damaging the rubber gaiter. Smear some Ceratec or TRW brake grease on the pin, do not be tempted to push any grease down the hole where the pin slides into caliper body as the hole is a dead end and if too much grease gets in there it will not compress and escape like air (you will notice are some flats running the length of the pin, sometimes only 1 but may be 3 flats) this is to allow air to escape when pin is pushed in). Take the pins out one at a time as sometimes top and bottom pins are different, on some brakes the bottom pin may have a rubber seal attached. You need to use 'rubber friendly' non-petroleum based high temperature grease, normal petroleum based grease will swell the seals and gaiters and degrade them.
inspect the pins for wear, if you think they are damaged new ones can be bought from
www.brakesint.co.uk for specific Honda Jazz bits (same site)
https://brakeparts.co.uk/shop/HONDA/JAZZ(Brakes International, based in Rochdale) for less than £10 for one caliper set (2 pins, 2 new bolts with threadlock painted on, new gaiters and a sachet of brake grease) I have used them, they sell Bremtech brand and from the contents of the kit look quality and are good value (the brake grease alone can cost a bit, and you don't need much so why buy a separate tube ?)