https://www.everythingairbrush.com/airbrushing-accessories/hoses-adaptors/regulators/professional-filter-regulator-to-suit-piston-type-mini-compressors.html
Theres one for an as186 compressor.
Approx £15.
Very similar looking one on ebay for £9.99, item number 191265916762
Found some cheaper, but they didnt have useful ranges on the guage, you should pay attention to the increment size on the dial, and if its in bars or psi etc.
Edit; screwfix will probably have the adapters you need cheap enough too, or perhaps wickes, or a local plumbing / hardware shop.
Its a 1/4" to 1/8" BSP connector that you need, depending on the threads male to female.. male to male... etc il let you work out what combination of ends you need when you find the huge range of fittings.
The right ones to suit and a roll of ptfe tape to seal the join and your good to go.