Multiple shipping options together with different product types and free delivery opt

I need to think ahead as client will be eventually wanting international shipping and currently she wants the following:

(Im assumning its best to keep it on the checkout.php page since this handles shipping address details and looks neater altogether)

1. royal mail special delivery which I charge £7.00 for (its insured)
2. signed for option at £4.00 (its not insured)
3. free delivery if collecting from the shop
(also gift vouchers have a shipping of 99pence / all other products have a shipping of either the above 1 or 2) but both regular products and gift vouchers can obviously be picked up from shop.

in my products database, I am storing either a 1 or 0 for the shipping (1 = regular products / 0 being gift vouchers).

then on my checkout page I would have a radio form for the above free options (£7, £4 or shop collection).

On my cart.php page Im assumning to set session variables to store either the product shipping (either 1 or 0) and on the checkout page for the radio form I would set session variables to store either. £7, £4 or free collection).

Im assumning this approach makes sense in my mind, but wanted to get some feedback on it (obviously currently its not working) and I am a bit stumped to what shipping calcualtions I should use in ecart object.

(currently I have a previous working system where the ecart shipping rules allow for dectection for a product to be either a regular product (£7 default shipping) and a gift voucher (99pence shipping) and i got a checkbox that allows a sessions to be stored to calculate free shipping if customer choses to collect from shop. (but this approach needs to be modifed due to client wanting the customer to have a third choice (the newly included £4 shipping option as stated at the beginning).

Please, could I get some advice on how to best tackle this from my lengthly description (Im known to ramble on) :)

Chris