Unfortunately, little is known about pre- or para-Roman body-painting and tattooing traditions in Great Britain to the point we don't know which particular designs, if there were any, were used.

That said, there is no shortage designs you could select inspiration,without any certainty (even less guarantee and even a fair deal of presumption against) they were used as body painting or tattooing motifs, as for example :

• Iron Age British coinage, importantly influenced by mainland Gaulish and, after the Gallic Wars, Roman coinage that you can get some examples on the British Numismatic website for between the IInd century BCE to the Ist century CE.

• A common source of inspiration in modern reconstructions of Pictii's tattooing is often found in the Pictish Stones, whose motifs are either obviously zoomorphic, possibly representing an object (as the mirror and the comb) or seemingly abstract. These, however, are not really contemporary of the period you're interested for and, as late ancient or early medieval, posterior by some centuries.