There's two things there. One is access to MPs and Ministers, The other is money donated to a party.
Access is relatively straightforward. Yesterday I spent the best part of an hour with my local MP on a complex policy topic. Also yesterday a mate spent time with a Minister, again on a policy topic.
In each case it was a matter of requesting an appointment. We are both ordinary people, not lobbyists or rich and famous.
Our representatives seem to be very accessible, even meeting in cafes sometimes.
Fundraising is a different beast. Some donors support multiple parties. Some support the one they agree with. Some donors seem to manage a nudge nudge wink wink with supporters of their industry. Can't possibly imagine which Deputy PM might be involved in anything like that.