What skills r needed to climb safely

Hope to start a ten week tree surgery course soon but unable to afford the 3day treeclimbing course prior to it.
Have some tree climbing experience , 2years tree protesting , helped put up about 8 platforms. Have also been rock climing with freinds some years ago. Unfortunatly no longer in contact as i would ask them. Bottom line i need to provide some evidence ( letter poss) that i can climb. and would like to know what such a letter should containe. any info would be fantastic . many tanx could you email me some advice as well as post it here for others many many thanx This email address is being protected from spambots. You need JavaScript enabled to view it.