Thanks for your replies.
I thought the seed holds the final balance etc no matter what wallet I use it in?
I was not sure if the original spend from Electrum would eventually get returned to my balance in my Multibit wallet or not, or can it be returned to my elctrum balance. I read somewhere about Electrum not getting change, I do not know if that means receiving payments? This is where I am getting too technical for myself
If Electrum can get the payment I sent returned (eventually) I will have my coins saved?
The seed is the "starting point" for creating addresses/private keys... it is the private keys that control the coins. The idea being that as long as you have the seed, you can regenerate the same addresses/keys should your wallet be lost/destroyed/corrupted (older non-HD wallets just randomly created addresses/keys so if you lost your wallet, you couldn't recover addresses generated after last backup), so you can get access to your coins (via the private keys)
Anyway, the problem is that wallets can use different "derivation paths" from one another... which means that the addresses/keys being generated from a seed will differ.
Think of it like a long hallway which has a large number of doors labelled: 1, 2, 3, 4, 5 etc. and behind each door is a room with a large number of addresses/keys, all different from the addresses/keys in other rooms... The long hallway is your "seed"... the doors are the "derivation path"...
MultiBit HD is using Door #1... and so you get all the keys from Room #1.... however, Electrum (when importing BIP39 seeds) uses Door #44... and will give you all the addresses/keys from Room #44...
For the record, the actual derivation paths are m/0'/0 for MultiBit HD... and m/44'/0'/0'/0 for Electrum... You can play around with this website to get an idea of how changing the path changes the addresses:
https://iancoleman.github.io/bip39/ (IMPORTANT: use an offline copy!!)