What Grading Would You Give For This 1930 Penny?

Agreeing with the comments above.

Just reading Dr Google.....The R in Britt.....the second leg looks rounded off as would be seen on the English Obverse. The Indian Obverse has a more upward curved end with a point. As only a couple of of London Obverse 1930 pennies have been sighted and authenticated that would put the chance of this being genuine at around 1500 to 1.
XAG, I don't imagine that you have the coin "in hand". But it would be worth the exercise in checking some of the known markers for a real 1930 against this specimen.

.XAG, back to your original question, I take it you're fly in fly out.
If you're in Adelaide on break, and Mawson Lakes is not out of your way, drop in to The Purple Penny. Have a chat with Mark and he will put you straight. I took a swag of stuff to him and he was straight up about what I had. Mark is also a member of this CoinCommunity.
Their website will give you the info you need about location and opening hours.

The coin pictured is not the coin that came with the letter

Update.

Thanks to everyone for their input. So I ended up passing on this particular example due mainly to time constraints regarding having the coins authenticity verified and graded. The coin did end up selling for 6k to another buyer. Whether this particular coin was authentic or not is something I guess we'll never know.

Thanks again to everyone for their input.