The internet is full of useful and inspiring information for making costume. The difficulty is working out what is Kentwell-appropriate. The purpose of this page is to point you in the right direction.
The first place to head is The Elizabethan Costume Page, run by Drea Leed. This site is a wealth of information and resources. It's major downfall is that the links seem somewhat indiscriminate and vary hugely in quality; don't assume that because it's linked from there it's correct.
The most useful sections of that site for us are these:
Festive Attyre is another wonderful site. The most useful aspect for Kentwellies are the galleries of period paintings - ideal for getting a grasp of shapes and colours. It covers clothing from the late fifteenth to the late sixteenth centuries and focuses largely on Italian dress, so not everything there is relevant to us, but a lot of basic construction can be learnt from it. The most immediately relevant garment there is her italian working class dress which, if made in wool rather than cotton, would pass costume check. I would avoid the Italian chemise patterns on this site as they are put together quite differently from how Rosemary suggests.
It's also worth spending some time reading Mode Historique. It's a multi-period site that largely focuses on Elizabethan nobility. The costumes themselves aren't relevant, by and large, but the techniques are sound. The section on boning types is particularly good; I've been using cable ties with great success.
I'd also recommend the diaries on Jessamyn's page. Again, she's aiming for a completely different social class but the construction information is very clearly laid out, particularly for the florentine gown. The finished dress is drop dead gorgeous and the site is well worth visiting just to drool.
RavenDreams has a guide to making period-looking spectacles.
Basic sewing techniques, designed for period costume, are illustrated here.
Whaleys sell linen and, although I've yet to buy anything from them, they were very prompt at sending me samples. I've no idea what their discount linen is like or whether it's suitable for Kentwell.
Fabric of Time have been recommended on the Kentwell list, but I've never used them. laurence (at) fabricoftime.freeserve.co.uk
Bernie the Bolt (tel 0208 502 6790) has a good reputation for both linen and wool.
The Tudor Group sell linen and linen thread and I've been very happy with the stuff I've bought from them.
Dave Rushworth sells utterly drool-worthy wool but, unfortunately, the contact details I have for him are out of date.
The Colchester Remnant shop (01206 763432) is staffed by reenactors and they always have good stuff in. Their range of linen is excellent and well priced and they usually have good wools, too. Plus they're nice people.
If you're near by, there's a stall on Norwich market that does excellent wool, although it is on the pricey side. He tells me he will be getting linens in shortly and anticipates pricing those at around the seven pound mark. John Lewis in Norwich are useless for fabric but they do sell metal boning.
Cable ties can be had from any DIY/electrical type store.
For hooks and eyes, buttons, aiglets, dried frogs, and Tudor just about anything try Annie the Pedlar. She's hugely helpful and she's a Kentwelly, too. Plus, if you decide all this is beyond you, she makes first rate Tudor costumes.
ShoesI get my shoes from Pilgrim Shoes. I have three pairs. I wear them all year round - reenacting or not - and I love them to pieces. Chris is a Kentwelly so, if you tell her your role, she'll tell you what's appropriate. Highly recommended.
When I was in Fairfax, the shoemaker to go for was Kevin Garlick. I have a pair of his seventeenth century soldier's latchets. They're excellent: high quality, and very sturdily made. I had a problem with my first pair - one was a too tight. He remade them promptly at his expense. Again, I'm very happy with both the quality of his work and his service. He is, however, getting on for twice as expensive as Pilgrim Shoes, although his work is much more sturdy.
Plantaganet Shoes also have an excellent reputation and, although I've yet to buy anything from them, they've answered email queries promptly. Again, more expensive than Pilgrim Shoes, but the stuff on their website looks pretty.