First of all, congratulations to Liza on the birth of daughter Isabella, and to Martin and Norma on their new grandchild.
Second - £45 is well worth it. I have studied Martin's playing on and off for 45 years, from records and live performances and I have learned so much -even if I still can't quite get the hang of Scarborough Fair from the first Fontana album! (Anyone got a transcription?) Some of his session work for other singers back in the 60s was fabulous - guitar accompaniment to Isla Cameron singing the Black Freighter, for one.
Not many musicians change your life. Hearing Martin Carthy for the first time changed mine.
You wouldn't have to even take a guitar with you to the workshop. Watch, listen, absorb. Later, do try this at home!