Fence & Decking Paint Sprayer
Energer ENB770SRG 100W Electric Spray Gun 240V
Energer ENB770SRG 100W Electric Spray Gun 240V - £4.99 @ Screwfix!
OR
Wagner Fence & Decking Paint Sprayer for fences, sheds, decking or garden furniture, covers 5 m² in 9 min, 1400 ml capacity, 460 W, 1.8 m hose
https://www.amazon.co.uk/gp/product/B01M6XZIZY/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&th=1 - £49.99 @ Amazon!
Both decent deals IMO depending on your needs/budget.