Calculation on booking form

Hello all

I would greatly appreciate some advice on how to achieve client-side calculation on my company booking form, using Javascript.

The total amount for accommodation is calculated based on the room type (single or twin), zone chosen and meal plan (which then assigns a certain rate per week, so for example Single room, Zone 2, Self Catering would be £165 per week). There is a table of rates here :

The code would then use the arrival and departure date to calculate the number of weeks, add a booking fee of £50 and output the total amount.

The form is located here:

Any assistance would be very much appreciated!

Thanks in advance