just had estimate for a bimini & new covers adding up to about £3k but they want half up front-is this normal? worried about losing it in current climate. Also they've given me an estimate not a quote, should I insist on a quote.
It's what one might expect of a small company having its normal line of working credit squeezed by its bank. IMO dig deeper into its financial history, if possible. Discuss your concern with the owner. Of course there's a rather greater risk of sudden insolvency, so contract that the materials purchased for the task are YOUR property - and make stage payments such that the goods are clearly yours - and identified as such.
You might want to consider it from their point of view - someone they've never met before comes and asks them to fork out a load of their time and materials to make a canopy for which they've little realistic chance of finding another buyer should you vanish or refuse to pay up. I'd also go the credit card route.