Large Mercator projection map/image of the UK

[Greenbank]

Anyone got a large (the bigger the better) Mercator¹ projection image/map of the UK?

The GPS software I used (GPS Trackmaker) allows you to insert a map image and I'm going to merge all of my GPX files from rides I've done into one and plot this on said image for a grand "Here's where I've been on the bike" map.

If I get a spare few hours I may try to grab, and stitch together, screenshots of 50km x 50km blocks that www.streetmap.co.uk can display on its lowest zoom setting.

At 5 pixels per km that's a very very big image, but that's the kind of thing I want.

1. Or any other projection where, for a rectangular image, the corners on the each side of the image have the same longitude, and the corners at the top have the same latitude, and the bottom two corners have the same latitude.

[Greenbank]

FWIW the UK is covered by 56 (although many are partial, such as OV which only shows land at low-tide) 100km x 100km squares designated by two letters under the national grid system.

Each of these is divided into 100 sub-blocks in a 10x10 square.

This means there are, at most, 5600 blocks to cover the UK.

Each streetmap page contains 25 of these (5x5) so I can get all of the required images in 224 separate visits (more likely 250 with some duplication) to www.streetmap.co.uk. Boring but scriptable, and it won't put that much strain on their webserver(s).

This covers the UK with a set of 70x130 5km square images. At 50x50 pixels per image that will give me a final image of 3500 x 6500 pixels.

Perfect.