Multiple Shipping Options Based On Weight?

[TR-UK]

Hi guys I'm looking for a little help.

My shop is pretty much ready to go live, the only hold up i have is the inadequacy of the shipping options at present.

I would like to set standard shipping rates based on TOTAL weight of products in the cart, but then have the option of adding drop downs for Signed Delivery, Special Delivery and Saturday Delivery at flat added amounts.

The equation would look something like this:

Total Weight Of Items= 750g  = Standard Shipping Based On Weight = £4.99
                                                   Signed Delivery = Standard Shipping Cost Based On Weight + £0.99
                                                   Special Delivery = Standard Shipping Cost Based On Weight + £4.99
                                                   Saturday Delivery = Standard Shipping Cost Based On Weight + £9.99

Does anyone know of a plugin or module that will enable me to do this without having to add a ridiculous number of shipping options?

Any help would be appreciated.

Thanks