Many thanks for Farrow contact & to all others who have replied. I have emailed them for a quote. Will advise outcome: if push comes to shove back to Plan A: the dreaded scraping!
Many thanks for those who recommended the Farrow System.
The hull was blasted using this system last week with excellent results and no adverse effect on the limpetite. Job took about 8 hours including clean up so saved this septuagenariun many back breaking hours. I can strongly recommend Tephratec (Tel: 0845 370 1990) for those in need of bottom stripping. Pics are available before & after if I knew how to post them.