Shipping Cost

I am trying to set the shipping cost in the tab but not sure what is the correct format? I only want to sell in uk and i’ve tried loads of variables:

GBR:4.99 GBP
GBR 4.99 GBP
4.99 GBP
etc

but none work, i always get an error saying the shipping value isn’t set. The example isn’t very clear (product. Example: US:024*:Ground:6.49 USD,US:MA:Express:13.12 USD)

any help would be great.

thanks
stuart

https://ww.wp.xz.cn/plugins/woocommerce-google-merchant-center-feed/