I would say that almost all Billing Boat kits require a high level of experience to build. This is mainly due to their interpretation of what 'instructions' mean!
Having said that, if you have built a wooden hull before AND if this particular Cutty Sark kit is a model you simply MUST put together -say for personal reasons- then you need to 'google' all over the place and study the different suggestions for hull-planking. It may be that you will find build logs from others who have actually built this Billing kit. Have a few extra lengths of strip-wood on hand in case you need to re-do something.
If you don't mind buying some other kit first, then some members here can surely recommend something with helpfull, easy-to-understand instructions.
I printed out a few google posts as an aid to planking my Fisher hull. Of course I was going to cover the hull in glass fibre after planking so a certain amount of 'leeway' was available for poor planking work. I don't now how much wood filler you can add to a Cutty Sark hull without spoiling it.
You'll surely get help here soon when a few more wake up for the new year!
George